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New documents released by the Arlington Police Department show the driver in a fatal crash and shooting last Wednesday in Arlington may have been under the influence of drugs during the incident.

On Monday, Tarrant County District Attorney formally charged Thomas Harper with murder, manslaughter and two counts of endangering a child.

Arlington Police say Harper caused two crashes, one that killed Najee Nasir, on Collins Street in Arlington, then opened fire, killing an 18-year-old C.J. Robinson.

NBC 5 obtained court documents that give more insight into Harper's behavior moments after the incident.

Search warrants issued by an Arlington Municipal judge just after the fatal crash and shooting showed that Harper had cannibinoids -- which are active in marijuana -- in his system. The search warrants included blood and urine samples, which were administered by Arlington Memorial Hospital.

That intoxication, according to the warrant, caused the wreck that killed Nasir and is the basis of Harper's manslaughter charge. Witnesses, including bystanders and police, referenced in the warrant describe Harper as seemingly drugged after the wreck.

"Witnesses informed officers that Thomas Harper appeared 'high.' He was making erratic statements and telling bystanders to 'get away,'" according to the warrant. Those bystanders were reportedly trying to help Harper and the two toddlers in his totaled SUV.

In the search warrant, officers say Harper “exhibited unusual behavior; he kept looking up at the sky and mumbling, saying incoherent statements…he was unresponsive to questions."

But the warrant goes on to say that when Harper had been released from the hospital and taken to jail, his statements finally began to make sense and that "he appeared sober and remorseful."

Harper will be moved from the Arlington jail to the Tarrant County Detention Center Tuesday morning. A judge raised his bail to $650,000 over the weekend.

Editors Note: NBCDFW originally reported incorrectly that Harper was charged with intoxication manslaughter, we regret the error.